No. 6 [subtitled]

Shion is a gifted student who leads a typical teenager's life. His normal life becomes anything but when a chance encounter with a strange boy leads Shion down a dangerous path.

Shion is stripped of his elite privileges and cast of of paradise. A mysterious parasite is loose in the city, and Shion is unjustly arrested. Meanwhile, Safu decides to study abroad.

After a daring escape from No. 6, Shion learns that he has become infected. With Rat's help, they remove the parasite from his body, but not without consequence. After analyzing the specimen, Shion comes to a horrible realization, one that threatens to destroy his former home, and rip his friendship with Rat at the seams.

Shion refuses a place to stay from his mother's friend . Inukashi blames Shion for Rat becoming soft over the years, and Shion makes a decision that could greatly affect his and Rat's lives.

The death toll is slowly climbing. The mysterious parasites claim another victim, this time in the Twilight House, where Safu's grandmother lives. Rat suddenly faints during a theater performance, and at the same time in No. 5, Safu faints as well, but not before she hears a quiet song in the wind...

After returning to No. 6 to gather her grandmother's belongings, Safu notices many strange things around her: objects that should be there are missing. Soon after, she is taken away by city officials. Rat catches wind of this from Shion's mother, and knowing that Shion will die trying to save her, is unsure what to do with the information...

Rat contacts Dogkeeper to gather information about the correctional facility. Meanwhile, Shion discovers Safu's old coat while shopping at a used clothing store. After piecing things together, Shion decides to make his way to the correctional facility himself, but not before a confrontation with Rat.

Shion and Rat head to the Western District in a mad dash to save Safu. On their way they meet up with an old man, known by Rat, and the first person to survive the parasite. Shion learns an unbelievable truth about Rat, as well as the real reason behind the creation of No. 6.

Holy Day is getting closer, and after gathering information about it, Rat, Shion, and Inukashi learn about some sort of cleansing operation that will take place. Meanwhile, the rumble of tanks breaks up the city wide celebration in the streets of No. 6...

After being herded into the correctional facility along with the townsfolk of No. 6, Rat and Shion fight their way through the throngs and begin searching for Safu. Shion knows exactly where to turn as they make their way around the complex, which worries Rat. After fighting through many obstacles, they finally find Safu, but are horrified at the sight that lies before them.

The Holy Day is finally here, and chaos soon erupts around No. 6.